Precision optical model of asymmetry emission band of red light emitting diodes and its application in improving the color rendering index of white LEDs

We have proposed and demonstrated a precision optical model for red light-emitting diodes and applied this model to improve the color rendering index of phosphor-converted white light-emitting diodes. The inherent asymmetry properties of red light emission bands have been conquered and effectively modeled. The accuracy of the red light optical model is confirmed with the experimental spectrum and verified by normalized cross-correlation. In an application, the Gaussian functions-based mathematical model is applied to simulate the emission spectrum of white light with and without adding red light. The supplement of red light is optimized to improve the CRI index of output white light. As a result, the color performance of white LEDs is improved when the CRI value significantly increases from 79 to 93 by adding an optimized amount of red light. The effect of added red light on white-LEDs properties has been investigated including correlated color temperature, output lumen, CIE-chromaticity coordinates, and luminous efficiency of radiation. In addition, the effect of adding red light on color rendering quality of output white light is studied with the IES TM 30–18 application.